Combustion gas electrical generator



BIB-11 Dec. 15, 1964 3,161,790

W. H. PERCIVAL ETAL CGMBUSTION GAS ELECTRICAL GENERATOR Filed July 19, 1961 'SEAM Wm.

United States Patent Q 3,161,790 COMBUSTION GAS ELECTRICAL GENERATOR Worth H. Percival, New Baltimore, and Michael T. Tsou,

Farmington, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed July 19, 1961, Ser. No. 125,135 8 Claims. (Cl. 310-11) This invention relates to magnetohydrodynamic generators and particularly to such generators utilizing combustion gas in an internal combustion engine.

It has been proposed to generate electricity by passing a conductive gas through a magnetic field and collecting the electrical current induced in the gas. It is the purpose of the present invention to apply this principle to internal combustion engines which utilize the high temperatures therein to produce conductive gases for the magnetohydrodynamic generation of electricity. The electrical energy thereby produced can be used to replace the customary electromechanical generator. This invention is applicable to any reciprocating internal combustion engine, but is especially well suited for very large diesel engines where a large volume of gas is available to give rise to practical quantities of energy.

The invention is carried out by providing in a reciprocating engine a high velocity stream of very hot conductive gases, imposing a magnetic field transverse to the stream and collecting the current generated within the gases.

The above and other advantages of the invention will be made more apparent from the following specification taken in conjunction with the accompanying drawings wherein like reference numerals refer to like parts, and wherein:

FIGURE 1 is a schematic representative illustrating the theory on which the invention is based;

FIGURE 2 is a cross section view of a portion of an internal combustion engine according to the present invention; and

FIGURES 3a, 3b, and 3c are a series of graphs illustrating the current outputs of the generating system according to the invention.

According to the Well known Faradays Law of electromagnetic induction, when a conductor moves relative to a magnetic field an electromotive force is induced therein and current will flow if the conductor is made part of a closed circuit. In the art of magnetohydrohynamics, a high velocity conductive gas is used as the conductor and a pair of electrodes adjacent the stream of conductive gas carries off the current induced in the gas. This is illustrated schematically in FIGURE 1 wherein a magnet having inturned pole faces 12 form a gap through which a stream of conductive gas 14 (represented by the arrow) is made to flow, and a pair of electrodes 16, one on either side of the gap, carry the current generated in the gas to an external load 18. According to the Faraday theory, the direction of current flow in the conductor is mutually perpendicular to the magnetic lines of force and the direction of conductor motion. Accordingly, the electrodes 16 are parallel to the plane of the magnetic field and the direction of gas flow in order to present a large surface to carry off the induced current. Although gases may be rendered conductive by heating them to temperatures exceeding 2000 F. to thereby cause ionization, the conductivity and hence the electrical generating capability is much improved by using considerably higher temperatures. The conductivity can be further increased by seeding the gases with easily ionized materials, such as the alkali metals.

According to the present invention as illustrated in FIGURE 2, an internal combustion engine 20 such as a 3,161,790 Patented Dec. 15, 1964 diesel engine includes a plurality of cylinders 22 and pistons 24. Each cylinder has the conventional intake and exhaust valves 26 and, in addition, has a combustion (or precombustion) chamber 28 in communication therewith. Combustion chambers are often used to improve the combustion characteristics of diesel engines, and in the instant invention, serve the additional function of providing a gas flow suitable for the generation of electricity. Specifically, the combustion chamber 28 includes a mouth portion 30 opening into the cylinder, a spherical chamber 32 into which fuel is injected by an injection nozzle 33, and a duct portion 34 of reduced cross section connecting the chamber 32 with the mouth portion 30. The combustion chamber 28 has a high temperature refractory liner 36 such as zirconia and the mouth portion 30 contains a porous refractory regenerator 38 which may consist of a porous zirconia plug or Wafers. The duct portion 34 contains near the wall thereof a pair of platelike electrodes 40 which are made of graphite, tungsten, or other suitable high temperature conductive material. A magnet 42 adjacent the combustion chamber has its poles situated on opposite sides of the duct 34 so that a magnetic field passes through the duct in a direction generally parallel to the planes of the electrodes. The magnet 42 may be of the electric or the permanent type, and if an electromagnet is used, obviously the current may be supplied from the current produced by the generator system.

During engine operation, fresh air enters through the intake valve and is compressed during the usual compression stroke and passes through the regenerator 38 and duct 34 to the combustion chamber 32. The regenerator which has been heated by combustion gases during previous operation raises the temperature of the air charge to about 3000 F. Fuel is then injected through the injection nozzle 33 and burned. The resulting combustion gas will attain a temperature of 4600 F. or higher, and hence tends to ionize to become a fairly good conductor. However, should it be desired to increase the conductivity, then the gas is seeded by mixing an easily ionizable material such as potassium, potassium carbonate, or other alkali metal therewith. This is accomplished by mixing a small amount of the seeding material, for example, up to 1 percent of potassium carbonate, with the fuel. The conductive gases are then discharged through the duct 34 (as shown by the arrow) and the regenerator 38 into the engine cylinder 22 during the power stroke. The regenerator is heated by the passage of the gas therethrough. Due to the geometry of the combustion chamber and the high pressures developed, the gas attains a velocity of 0.7 to 1 Mach as it passes through the duct. The gas temperature drops to about 4000 F. before reentering the regenerator and to 2100 F. in the engine cylinder wherein normal engine power is produced. The high velocity conductive gases passing through the magnetic field generate an as described above. An electrical current is drawn from the gas by the electrodes 40 and the associated load circuit 44.

Since the operation of the combustion chamber is cyclical and since the gases are ionized sufiiciently well to become conductive only during the discharge through the duct, then the current produced in each chamber will be intermittent as shown in FIGURE 3a. By connecting a plurality of generator units in series so that their polarities are additive, a fairly continuous current ouptut may be achieved as indicated in FIGURE 3b and, if desired, may be filtered to achieve a uniform voltage level. On the other hand, the generator units may be connected so that the output takes the form of an A.C. current as shown in FIGURE 30 which, of course, may be acted upon by a transformer. Although the graphs of FIGURE 3 relate to current from two cylinders operating about 180 out of phase, it is evident that other suitable circuit arrangements may be derived depending upon the number of cylinders involved.

It is readily apparent that by means of the present invention a reciprocating engine such as a diesel engine may be equipped with magnetohydrodynarnic generators to produce a useful current output to thereby increase the net engine efliciency and to eliminate the usual electromechanical generator for the production of auxiliary power. Although the most apparent application of the invention is to large stationary diesel engine applications wherein a large volume of gas is used in each cylinder, it is obvious that refined embodiments of the'invention are applicable to smaller automotive diesel engines as well as to other reciprocating internal combustion engines.

It is not intended to limit the invention to the specific form described herein, but rather the scope thereof is to be limited only by the following claims.

We claim:

1. An electrical generator comprising a diesel engine, combustion means associated with a cylinder thereof to produce a high velocity stream of conductive gases having a Mach number between 0.7 and 1, means for imposing a magnetic field transverse to the stream, and a set of electrodes adjacent the stream to collect the electrical current induced therein.

2. An electrical generator comprising a diesel engine means associated with a cylinder thereof to produce a high velocity stream of conductive gas comprising a regenerator and a fuel combustion chamber, means for imposing a magnetic field transverse to the stream, and a set of electrodes adjacent the stream to collect the electrical current induced therein.

, 3. An electrical generator comprising a reciprocating internal combustion engine, a cylinder, a precombustion chamber, a duct connecting said cylinder andsaid chamfor collecting the electrical energy generated by the coaction of the magnetic field and conductive gases passing therethrough.

5. An electrical generator comprising a reciprocating internal combustion engine comprising means for producing conductive gases, 8. cylinder, a precombustion chamber, a passage connecting said cylinder and said chamber, a regenerator in said passage, magnet means for producing a magnetic field across said duct, and a set of electrodes within said duct for collecting the electrical energy generated by the coaction of the magnetic field and conductive gases passing therethrough.

6. An electrical generator comprising a multi-cylindcr internal combustion engine having a precombustion chamber associated with each cylinder and a duct connecting the chamber to the cylinder, a magnetohydrodynamic generator system including means for applying a magnetic field transverse to each duct and a set of electrodes in each duct to collect electrical current induced in the conductive gases passing therethrough.

7. 'An electrical generator comprising a multi-cylinder diesel engine having a precombustion chamber associated with each cylinder for producing conductive gases, and a her, magnet means for producing a magnetic field across internal combustion engine, a cylinder, at precombustion chamber for producing conductive gases, aduct connecting said cylinder and said chamber, a refractory lining in said chamber and duct, a porous refractory regenerator' in said duct, magnet means for producing a magnetic field across said duct, and a pair of electrodes within said-duct duct connecting the chamber to the cylinder, a refractory lining in said chamber and duct, a porous refractory regenerator in said duct, a magnetohydrodynarnic generator system including means for applying a magnetic field transverse to each duct and a set of electrodes in each duct to collect electrical current induced in the conductive gases passing therethrough.

8. An electrical generator comprising a multi-cylinder internal combustion engine having a precombustion chamber associated with each cylinder, a passage connecting the chamber to the cylinder, and a regenerator in the passage between the chamber and the cylinder, a magnetohydrodynamic generatorsystem including means for applying a magnetic'field transverse to each passage and a set of electrodes in each passage to collect electrical current induced in the gases passing therethrough.

Power: (maz .)*November 1959 by A. Kantronitz and P. Sporn, pages 62-65. 

5. AN ELECTRICAL GENERATOR COMPRISING A RECIPROCATING INTERNAL COMBUSTION ENGINE COMPRISING MEANS FOR PRODUCING CONDUCTIVE GASES, A CYLINDER, A PRECOMBUSTION CHAMBER, A PASSAGE CONNECTING SAID CYLINDER AND SAID CHAMBER, A REGENERATOR IN SAID PASSAGE, MAGNET MEANS FOR PRODUCING A MAGNETIC FIELD ACROSS SAID DUCT, AND A SET OF ELECTRODES WITHIN SAID DUCT FOR COLLECTING THE ELECTRICAL ENERGY GENERATED BY THE COACTION OF THE MAGNETIC FIELD AND CONDUCTIVE GASES PASSING THERETHROUGH. 